Another C**p Question

[Grim.Badger 15]

My mechanical knoweldge is really quite poor at the moment

I'm changing my cambelt and trying to follow Haynes but I don't understand a couple of things.

1. How the hell do I know if the engine is at TDC?

2. Is the Crankshaft pulley the wheel that drives the auxillery drive belt and is attached to the Crankshaft sprocket ?

3. Could someone explain the running in procedure for a new belt in a way that is easier to follow than Haynes? Maybe I was just tired but it seemed a bit confusing

 

I've tried searching but can't find a decent explanation of cambelt changes.

 

Cheers

[Miles 331 1 Cars]

The engine doesn;t go anywhere near TDC when changing the belt, It's more like MDC (Middle dead centre), But You need a couple of locking pin's (Bolts or drills most people use) and the cam wheel lines up with a hole in the head at the back of the cam, you can feel it rather than see it but with the engine out it's even easier, The bottom pulley again line's up with a mark in the side cover of the engine, I'm sure if you do a search you'll find some pic's on this or find a old Joke book which cover's most procedures quite well

[Grim.Badger 15]

The engine doesn;t go anywhere near TDC when changing the belt, It's more like MDC (Middle dead centre), But You need a couple of locking pin's (Bolts or drills most people use) and the cam wheel lines up with a hole in the head at the back of the cam, you can feel it rather than see it but with the engine out it's even easier, The bottom pulley again line's up with a mark in the side cover of the engine, I'm sure if you do a search you'll find some pic's on this or find a old Joke book which cover's most procedures quite well

 

Is it simply the case then that when the engine is at TDC/MDC the bolt holes line up?

[Higgy 0]

As Miles said, just lock the crank pulley and the two cam pulleys with drill bits etc. Then when you remove the old cambelt the engine can not rotate, so you can not screw up the timing.

 

 

Here is a pic of my Mi16 with the cam pulleys locked (I used exhaust manifold bolts from the 8V):

 

Here is the crank pulley. Either undo the 4 bolts and remove outer pulley or just place drill bit through circled hole and line it up with the slot on the block casting.

 

 

Hope this is of some help.

 

Higgy.

[Grim.Badger 15]

Sorry I'm not making myself clear

Haynes goes on about turning the engine AFTER the new belt is on, and says things like "turn it to TDC" iirc. This is part of the running in of a new belt as well as checking that everything lines up.

[Higgy 0]

Ok got you.

 

With the Mi16, you put the belt on, rotate the engine (socket on crank pulley bolt) a number of times then get the engine crank pulley back into its locking position, the cam pulley locking holes should (must) line up also.

 

If the locking pins go back in, then your timing is spot on. If all the locking pins dont go in then the timing is OUT

 

When I did mine there was something about lining up the white marks/lines on the cambelt with points on the pulleys. But I've just been through the Haynes, Pug & Cit rebuild manuals and can not find it.

 

I recommend that if you are still worried, when you start the engine for the first time, disconnect the injectors and turn the engine over just a bit. Then re-check if the locking pins fit.

 

Higgy.

[nick 3]

You don't even need to use the timing marks, you can make your own.

 

I just rotate the engine until you can feel it under no compression (hard to explain, but it gets to, like a "dead" spot in the rotation where the crank moves easily a little bit in both directions) then just mark the cam wheel and the rocker cover and do the same with the crank pulley and the block.

 

As long as these marks still line up when the belt goes on it's timed up fine.

 

Nick

[M_R_205 5 1 Cars]

im also about to fit a cambelt to my mi16 but luckily the engine is out, this may sound stupid but if you rotate the engine it it dosent all line up, do you take it all off and start again?

also, how do you go about tennsioning it, the tennsioners i have aunt spring loaded they rotate off crentre so to say.

 

thanks for the pics higgy, it all makes a bit more sence now

Edited February 22, 2007 by M_R_205

[Richie-Van-GTi 71 2 Cars]

the off centre type of tensioner has a square hole, you should find either a 1/4 or 3/8th drive fits this hole just nice. Use that to hold the tensioner so the belt is tight then fasten the 13mm nut on it so it cant loosen back off

[lagonda 42]

Done this job recently on my 1.6. Don't really see why you need to establish where tdc is ... provided your timing pins line up, that is all that matters. In actual fact, if your head has been skimmed, they won't both go in unless they're a little on the slim side. My pins lined up spot-on before I removed the head. I only had a light skim done, just enough to get it dead flat, but it was still enough to mean my tight-fitting pins didn't both go in. Using a slightly thinner pin for the camshaft sprocket worked well. Moving the belt on the cam sprocket by one tooth put things well out, so proved my initial setting was correct.

The pin line-up sets the crank at literally middle dead centre, with the pistons all lined up halfway down the bores. This is to ensure that there is no risk of the valves hitting any pistons while the cam is being turned.

Yes, the auxillary drive belt pulley is the crank pulley, the cam driver behind is the crank sprocket.

Assuming you have the spring loaded tensioner like mine, it took me a while to work out how it was set! Firstly, the tensioner cam, mounted at the top of the rear of the block, is NOT an adjuster. Its purpose is simply to relieve the spring tension as an aid to fitting the belt. On the exhaust side it's spindle ends in a ludicrously tiny squared shaft with I think a 16mm nut to lock/tighten it. I think the square is 6mm: it is VERY hard to turn to engage the cam as it is loading the spring. My correctly sized spanner kept slipping off, but then I found the drive end of a quarter inch socket was a perfect fit, so find one that you have an allen key to fit the other end, and there you have the perfect tool for the job!

I then found the cam wanted to ride up the outside edge, so you need to have the 16mm locking nut fairly tight, but loose enough to be able to turn the square. You are only turning it through 90 degrees of course, and remember when releasing it, the spring pressure will make it snap back.

To do the actual tensioning, you need to loosen both nuts (11mm I think) on the tensioner body AND the 16mm locking nut for the square shaft. With everything loose, the tensioner literally sets itself, so all you have to do is retighten the 3 nuts. From recollection I think Haynes says turn the engine over a few times to allow the belt to stretch, then loosen and tighten the bolts once more, but I think it better to go for a drive afterwards & do the procedure one more time, thus allowing for the belt to bed into the sprocket teeth, and a little further initial stretch. Good luck!